1. Field of the Invention
This invention relates generally to construction safety apparatus and, more specifically, to a Hole Cover.
2. Description of Related Art
Large construction projects involving the erecting of multi-floored commercial buildings generally include the structural feature of poured concrete floors. The concrete floors provide excellent durability and stability, and furthermore, allow great flexibility in configuring and re-configuring interior walls, because the vast majority of them are non-structural. However, the use of concrete for the floors includes some inherent challenges during the completion stages of the building (as well as during later improvement projects). Once the concrete has been poured and cured, it is difficult and expensive to cut new holes or penetrations through them. In order for required plumbing, wiring, and other infrastructure components to pass between building levels, it is necessary that numerous penetrations be provided through the concrete floors. Consequently, quite a number of penetrations are created in the forms prior to the concrete being poured. Until the interior (typically non-structural) walls are built, therefore, virtually all of these penetrations are out in the open. These open penetrations would provide a great safety risk to workers at the site during construction (e.g. tripping and falling); this risk is prohibited by regulation, and regular site inspections will result in citation if unprotected penetrations are discovered.
As shown in FIG. 1, a partial cutaway side view of the generic concrete floor 10, a penetration 12 is a generally circular bore formed to extend between the top surface 11A and the bottom surface 11B of the floor 10. The floor 10 typically has a thickness T(F) of between four and six inches (4″ to 6″). Penetrations 12 can be of a variety of diameters D(P), depending upon their intended purpose, but they generally range between two (2) inches and eight (8) inches in diameter. It is not uncommon that there be several hundred of these penetrations 12 in any multi-level commercial building. As discussed above, each of these penetrations 12 must be covered in order to prevent personal injuries or citations from inspectors.
There have been several attempts over the years at solving the expense and inconvenience of plugging (and unplugging) these floor penetrations 12. One example was presented by P. D. Becker in U.S. Pat. No. 2,552,917. The “Universal Plug Button” of Becker is a simple device defined by two components—the cap 24 (designed to cover the penetration in the deck 22), and the fastener members 26 extending beneath the deck 22 (or wall). The problem with the Becker device is that its two-part design includes fastener members 26 formed from one piece of spring-type metal, while the cap 24 is made from a hardened metal to insure that it is of the requisite durability. The fact that these two elements are made from treated metal adds substantial cost to the device 20. Due to the sheer number of penetrations [12] that need to be plugged, it is critical to maintain the lowest per-item cost as is possible. Also, the Becker design is not sufficiently adjustable to differently-sized holes [12]—this means that the builder must have a whole range of sizes of buttons 20, with each particular size of button 20 only suitable for one diameter of hole/penetration [12].
Another prior device is the “Stopper Device” of Wagner, et al., U.S. Pat. No. 6,360,779. This device is depicted in perspective view in FIG. 3. The stopper device 30 is a single molded piece, presumably made from plastic. The cap member 32 sits above the floor [10] when the device 30 is inserted into a penetration [12]. There is a cross-shaped stem 34 extending vertically down from the bottom of the cap member 32. Along the length of the stem 34 are a plurality of “radial vanes” 36. These radial vanes 36 are designed to flex (i.e. curl up) as the stem 34 is inserted into the penetration [12]. The spring force exerted against the walls of the penetration [12] by the curled vanes 36 will serve to center the device 30 on the penetration [12], and to retain it in position. There are at least two problems, however, with the Wagner device 30. First, the design of the vanes 36, while better than those of Becker, are still limited in their ability to accommodate to a wide variety hole diameters D(P)—if the hole is too small, the vanes 36 will not be able to curl sufficiently to allow the stem 34 to be inserted into the hole [12]. Also, the curled vanes 36 will create a force that opposes the removal of the device 30 from the hole [12]. This will not only make removal of the device 30 difficult, but it will tend to cause undesirable wear and tear on the vanes 36, which will lead to a shorter service life than is desirable.
Murkland, U.S. Pat. No. 7,581,361, depicted in FIG. 4, discloses yet another version of plugs for holes in concrete floors. The Murkland “plug” has a cap and four rigid “vanes” that extend down from the cap. The Murkland plug is retained within the hole because the outer edges of the vanes are slightly farther apart than the diameter of the hole being plugged. The base portion 44 is integrated and/or attached to the head portion 42, and so it can only fit a single-sized hole. A series of projections 46 are provided in order to create a space between the top of the slab [10] to accept a prying device therein to remove the plug 40 from the hole [12].
What is needed is a simple, low-cost, durable cover for penetrations in concrete floors that can each accommodate a range of hole diameters, and be installed and removed easily and quickly.